A plug-in electric vehicle is generally understood to be a motor vehicle that may store electrical supplied via an external electrical energy source, such as a socket outlet, for example, in rechargeable batteries of the motor vehicle for supplying power to an electric drive motor. Such plug-in electric vehicles are often referred to as PEVs or PHEVs. These vehicles are a subgroup of electric or electrified vehicles that also include, inter alia, so-called BEVs or battery electric vehicles. Fuel cell plug-in hybrid vehicles have, in addition to plug-in electric vehicles, a fuel cell on board that makes available additional electrical power. Fuel cell plug-in hybrid vehicles generally also have a high-voltage battery on board, which acts as the store for the electrical energy. This high-voltage battery is charged via the fuel cell and can be connected to an external electrical energy source via a power cable so that said battery is also charged from the power supply system. As a result, there are potentially two different charging possibilities.
A charger, which may be located on board the vehicle, is needed to supply electrical power from outside via the power cable. This charger converts and rectifies the feed voltage and current drawn via the power cable into a charging voltage and current suitable for the high-voltage battery. The feed voltage is generally an AC (alternating current) voltage and may be present as a three-phase AC voltage at 380 V, for example. Firstly, it needs to be converted to the amplitude required for the charging voltage, and secondly it needs to be rectified.
If such a charger is provided in the vehicle, it requires additional cost, weight, and space for installation. Particularly in the case of motor vehicles manufactured in high numbers, these factors need to be taken into consideration as they result in increased costs and larger dimensions for the motor vehicle.
If the charger is designed for the total power with which the high-voltage battery of the motor vehicle can be charged, it is relatively large, heavy, and expensive. Therefore, the general course of action is to design the on-board charger for a lower power. However, this means that the charge time is extended. A charger generally requires a transformer and/or electronics comprising rectifiers and control units. The transformers are very heavy for the required power. The high weight is a disadvantage for constant transportation in a motor vehicle. A transformer is understood to mean a voltage transformer for AC voltage.
A combined system for electric traction drive and battery charging may be provided such as described in U.S. Pat. No. 5,099,186 A. In such systems while in driving mode, the electric drive motor of the motor vehicle is fed by a high-voltage battery and provides the torque necessary for the driving mode. In the charging mode, the drive motor acts as voltage transformer and converts the system voltage drawn externally into a voltage as is required, after rectification, by the high-voltage battery for charging. As a result, a separate transformer is no longer required.
Other systems such as those disclosed in WO 2011/159 241 may use the converter and portions of the winding of the electric drive motor of the motor vehicle for charging standard single phase or Level 1 charging. The use of three-phase or Level 3 charging in this proposition would simplify the use of switches for the connection to the electrical power supply system but may result in a torque in the rotor of the electric drive motor. It would therefore require the additional step of decoupling the motor from the drive train.
Other systems that use a drive motor as a transformer for modifying the voltage for battery charging are disclosed in U.S. Pat. No. 4,920,475 A and WO 2010/057 893. Representative fuel cell vehicles are disclosed in US 2007/0287046 A1, U.S. Pat. No. 7,743,861 B2 and JP 2005310429A.
The disclosures the prior art patents and publications described above are hereby incorporated by reference in their entirety.